Alapimba,
You're probably right--I wish I had bought that from you, but I wasn't aware of this problem then. The other problem is that I do not know of anyone in my area who could install the new gears if I bought them, so I'd have to ship it to Scuderia Topolino or something. That would end up being expensive.
But first I need to check my tachometer against another one, since with 185/60-13 tires I'd have to have an overall ratio in 4th of 5.0 (rather than the stock 600D ratio of 4.37) to have that many revs at 100kph. From the information I have Fiat did not make a car with that ratio-- they were either higher or lower, so something is goofy here.
What engine revs do people with standard 600D transxles have at 100kph?
Jim